1. Field of the Invention
This invention relates, to a heat pipe type radiator for cooling heat-generating components.
2. Description of the Prior Art
In recent electronic apparatus, the heat-generating components such as LSI (Large Scale Integrated Circuit) are assembled in high packaging density on printed circuit boards and a large number of these printed circuit boards are inserted into a cabinet with a small spacing. Therefore, the heat generation rate within each electronic apparatus is strikingly increased, and design of the conventional forced-air cooling type radiator having a fan unit has reached its limit of cooling capability. In addition, in recent designs, the space for packaging each heat radiator has become narrower, and the heat radiation within the electronic apparatus has become an extremely difficult problem.
Now, a cooling structure is being used in which a heat pipe is mounted on a heat-generating component and the heat absorbed from that component by an evaporative section of the heat pipe is transported to a condenser section in the heat pipe to radiate the heat. Since heat pipes transport large latent heat by vapor with high speed, the heat pipes transport heat with a slight temperature difference between the evaporative section and the condensive section. In addition, since the heat pipes show excellent heat transfer performance, a heat pipe type radiator has been widely used to cool semiconductor elements such as LSI.
FIG. 10 is a schematic perspective view showing a conventional heat pipe type radiator. In this radiator, the heat-generating components such as a LSI 3 mounted on a printed circuit board 2 are brought into contact with the evaporative section (heating section) of a heat pipe 1 directly or through a transportation plate 4, radiation fins 5 of a plate type are directly mounted on the condenser section (cooling section) of the heat pipe 1. The generated heat in the LSI 3 is transported to ambient air through the plate fins 5. The structure of the heat radiation members on the condenser section of the heat pipe 1, may be the plate type shown in FIG. 10 or a type in which the fin and a heat conductive plate are one piece formed of extruded aluminum as shown in FIG. 11.
In order to improve the performance of electronic apparatus, however, the electronic components tend to be mounted in high density onto each printed circuit board, and simultaneously the spacing between adjacent printed circuit boards tends to become smaller due to insertion of more printed circuit boards into a cabinet. Accordingly, the heat generating problem has tended to worsen in recent years.
Therefore, the conventional mounting of the fins on heat-generating components encounters difficulty in dealing with the heat radiation from the conventional heat pipe radiator as described above.
For example, in the cooling section of the heat radiator shown in FIG. 10, dimensions a, b and c are determined by the size of the printed circuit boards 2, the spacing between the printed circuit boards 2 and the size of the cabinet, respectively, and therefore, the higher the density in mounting, the smaller the heat radiation space becomes. However, there are limitations on improvements of the heat radiation capability. For instance, with respect to the radiator shown in FIG. 10, the heat transported through the heat pipe 1 does not sufficiently conduct to the remote part Y located furthest from the heat pipe 1. Further, with respect to the radiator shown in FIG. 11, the heat radiation member 6 as a whole provides closer to a uniform temperature distribution, but the surface area for heat radiation is small. Thus, development of the heat radiation capability remains limited.